Process of manufacturing manure from raw phosphates.



UNITED STATES PATENT OFFICE;

WILHELM PALMAER, OF STOCKHOLM, SWEDEN.

PROCESS OF MANUFACTURING MANURE FROM RAXV PHOSPHATES.

No Drawing.

To all whom it may concern:

Be it known that I, VVjiLnnnii Pmmmnn. a subjectof the King of Sweden,and resident of Stockholm, Sweden, have invented a new and usefulImproved Process of Manufacturing Manure from Raw Phos photos, of whichthe following is a spcrifiration. a

The Patents No. 707886 and No. 748525 describe a. process ofmanufacturing tricalcic phosphate and bicalcic phosphate byelectrolyzing a solution of a salt of such a composition that an acidforming with lime a soluble salt is disengaged at the anode while abasic hydrate is formed at the cathode, such salts being for instancealkaline or ammoniac salts containing nitric acid. chloric acid,perchloric acid, etc, or a solution of a mixture of such salts, among:which small quantities of foreign salts, for instance chlorids, may bepresent. The manufacture of bicalcic phosphate is effected in such amanner that the mmoral-phosphate is placed in a. separate vessel whereit is acted upon b the acid solution formed at; the anode am dissolved,a suitable quantity of the solution formed at the cathode beingafterwardedded .to the acid solution of phosphate obtained toprecipitate bicalcic phosphate, While in manufacturing tricalcicphosphate the acid solution of the mineral phosphate is mixed at oncewith the whole quantity of alkaline solution obtained by theelectrolysis simultaneously with the acid solution; which has been takenout for dissolving the mineral-phosphate.

An essentiah novelty in the method described in the above mentionedpatents was that acid and alkali for treating even poor, up to this timeWorthless, raw phosphate can be manufactured in an economicallyadvantageous Way.

I have found that the method described in the Patent No. 748523 ofmanufacturing bicalcie phosphate, provided alkaline salts are used aselectrolyte and consequently bicalcic phosphate precipitated by means ofan easily soluble alkaline hydrate, has an essential advantage over. themethod known. be fore for precipitating hicalcic phosphate from an acidsolution of a raw phosphate by means of lime. If, to an acid solution ofa raw phosphate a solution of for instance hydrate of potassium or ofsodium is added in a quant1ty just suflicient to render theSpecification of Letters Patent. Patent-0d June 20, 1911. Applicationfiled February 5, 1907. Serial No. 355,943.

solution slightly acid, or plainly Iicutral, it is possible, byintrmlucing; the said alkaline solution in a tinely divided form andunder agitation, to obtain almost all of the phosphoric acidprecipitated in the form of nearly pure biealcic phosphate containingcitratesoluble phosphoric. acid Without admixture of tricalcicphosphate, in which latter the phosphoric acid is not citrate-soluble;the quantity of citrate-soluble phosphoric acid in the prcri 'iitateamounts to from 95 to 99% of the total percentage of phosphoric acid inthe original solution of raw phosphate. This is of a great economicalimportance as only bicalcic phosphate but not tricalcir ph-psphateexerts a manurial effect on all kinds of soil and consequently the worthof the product is generally determined by its percentage ofcitrate-soluble phosphoric acid, which as mentioned above corresponds toits percentage of bicalcic phosphate. If on the other hand lime-wash isused as a precipitating means, as is done in, several gluc nlills, wherebones are dis; solved by hydrochloric acid. or if a mixture of hydrateof magnesia and water is used, as has also been proposed, there can notbe prevented the complete saturation of the acid solution which occursin some places in the vicinity of the small particles of hydrate of limeor magnesium, whereby tricalr-ic phosphate is precipitated. The bicalcicphosphate manufactured in glue-mills which is precipitated by lime-washdoes not contain over of the total quantity of phosphoric acid in acitrate-soluble form and by hydrate of magnesia a still more unfavorableresult is obtained. Besides experience has shown that a so-calledretrogradation takes place, i. c. the percentage of citratesolublephosphoric acid diminishes in the course of time, when bicalcicphosphate precipitated by means of lime (and probabl also ifprecipitatedby means of ma nesial is kept in store. This depends on t e fact thatsolid particles of lime in the mixture, which hardly can be avoided,react on the bicalcic phosphate, and tricalcic phosphate is formed.-Inbicalcic phosphate precipitated with potash or soda in solution onthe contrary, no retrogradation can take place as experience has alsoproved. This fact that recipitatin by means of easily soluble a kalinehy rates a product which is almost entirely citrate soluble is obtainedno 'in a known manner so as to obtain a solution of hydrate of alkali,it may be after dissolving an alloy of alkali metals by water, andchlorin gas. The chlorin gas may be transformed in a known manner intohydrochloric acid for instance by causing it to combine with hydrogendisengaged at the cathode during the ekctrolysis, the reaction beingstarted by a suitable catalytic sub stance for instance charcoal orfinely divided platinum, or by leading the chlorin, mixed with steam,over incandescent coke, after which the hydrochloric acid is absorbed byWater. and an aqueous solution is obtained. By the hydrochloric acidthus obtained the raw phosphate is dissolved and then bicalcic phosphateis obtained by precipitating with a portion of the hydrate of alkalisimultaneously obtained. Afterward, after gathering the bicalcic phoshate, the remaining part of the hydrate of alkali simultaneouslyobtained is added, the lime remaining in the solution amounting to aboutof the original quantity in the raw phos" phate dissolved being mainlyprecipitated as a hydrate and the last traces of lime are precipitatedby introducing some carbon dioxid, after which the electrolyte isregenerated in the same manner as indicated in the Patent No. 7485-23.

, Chlorid of sodium and of potassium respectively being essentiallycheaper than the salts, such as nitrates, chloratcs and perchlorates ofalkali metals, mentioned as electrolytes in the Patents No. 707886 andNo. 748523, it may, depending on local circumstances, in some casesbecome more advantageous to work according to the method now described.

If it is desired to manufacture tricatclc phosphate by the method nowdescribed, it is etlected by adding at; once. to the acid sotuition ofthe raw phosphate the whole quan tity of alkali obtained by clertrolysisunder production of the acid used in dissolving the raw phosphate, tricarirphosphate be ing precipitated and gathered. after which theelectrolyte is regenerated hat I do claim as my invention and dcsire tosecure by Letters Patent, is

A process of manufacturing a chemical manure from raw phosphatesconsisting in subjecting mineral phosphate to the action of hydrochloricacid and adding a solution of the hydro'xid of an alkali metal to theacid solution of the phosphate for preci 'iitating the latter asbicalcic phosphate.

In testimony whereof I have signed my name to this specification, in thepresence of two subscribing witnesses.

VVILHELM PALMAER.

